Never ending period

Hi everyone! So for the last 3/4 years I've been having very long periods. Since getting the implant in my arm, my periods went from 4 days up to 2/3 weeks. Since the implant has finished working (in April 2016) I'm still experiencing very long periods. My previous was 4 days, so I thought "thank god I'm finally getting back to normal!" However this time I'm currently on day 15 and I am in agony with them.

Can someone advise me on what to do? Getting into a doctor is near enough impossible. They've said the next appointment is in 3 weeks?

Help☹️